Shielded IC Pad Structure with Ground Shield Cage
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Solution Overview
Problem
Integrated circuits face noise and spurious coupling issues due to signal routing, which existing ground shields attempt to mitigate but often introduce parasitic capacitance and reactance, complicating the interference protection.
Innovation Solution
A ground shield cage structure with tiled conductive ground elements and a set of ground strips positioned below the pad, where the ground strips are designed to reduce parasitic reactance and provide isolation by creating a shielded environment around the pad, including a top conductive ground element with an inner and outer perimeter, and sidewalls that surround the pad to minimize unwanted signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a ground shield plate is used to protect the pad from unwanted interference, then shielding effectiveness is improved, but parasitic capacitance between the plate and routing conductor or pad increases
Solution Approach 1:
The ground shield is divided into multiple discrete ground elements arranged in a tiled pattern beneath the pad, rather than using a single continuous ground plate. This segmentation reduces the total parasitic capacitance while maintaining shielding effectiveness through distributed grounding points
Solution Approach 2:
The ground elements are positioned at specific locations beneath the pad and signal routing, creating localized shielding zones where needed. The ground elements have different dimensions and positions optimized for their specific locations, with some elements closer to the pad and others closer to the routing
2Device complexity
If circuit routing is placed directly beneath the pad to save space, then device complexity is reduced, but spurious signal coupling between the pad and routing increases
Solution Approach 1:
Multiple ground elements are positioned between the pad and the signal routing beneath it, acting as intermediary shielding structures. These ground elements block the electromagnetic coupling path between the pad and the routing, allowing the routing to pass directly beneath the pad without causing interference
Solution Approach 2:
The shielding solution moves from a two-dimensional plane (pad and routing on the same layer) to a three-dimensional structure with ground elements at multiple vertical levels beneath the pad, creating vertical shielding barriers that block horizontal electromagnetic coupling
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution effectively isolates the pad from spurious signal coupling and reduces parasitic reactance, providing better protection against interference while minimizing the introduction of new reactance issues, thus enhancing the reliability of integrated circuits.
Implementation Method 1
A ground shield cage structure with tiled conductive ground elements and a set of ground strips positioned below the pad, where the ground strips are designed to reduce parasitic reactance and provide isolation by creating a shielded environment around the pad
Implementation Method 2
This however creates an additional problem in that the plate of the shield pad creates parasitic capacitance, or other undesirable reactance, between the plate and the routing conductor or between the plate and the pad itself
Data Source
AI summary
An integrated circuit pad structure includes a ground strip (206) positioned below a pad (101). In one example a conductive element (102) is coupled to the pad (101), and at least two tiled layers, positioned below the first conductive element (102) and positioned above the ground strip (206) are included. A conductor (203), may run beneath the ground strip (206). In a second example, a pad (101) is seated on a ground shield cage having a bottom conductive ground element (302) including several ground strips where at least one ground strip (116) is along a signal routing path. The ground shield cage further includes a set of stacked conductive ground elements, stacked to form sidewalls (209, 210) of the cage. The top conductive ground element (301) of the stacked elements has an inner perimeter and an outer perimeter, such that the inner perimeter surrounds the pad (101) and the top conductive ground element (301) is in the plane of the conductive element (102) coupled to the pad (101).